Relief valve



Sept. 4, 1934. J. A SPENCER 1,972,171

RELIEF VALVE Filed Sept. 8, 1950 wwf Il wir" 40 Patent 1,448,240.However, it is composed of a used only, that valvewould open. But thepres Patented Sept. f1, 1934 e e UNITED STATES PATENT OFFICE RELIEFVALVE John A. Spencer, Newtonville, Mass., assigner to General PlateCompany, Attleboro, Mass., a corporation of Massachusetts ApplicationSeptember 8, 1930, Serial No. 480,454

' 1 Claim. (Cl. 277-51) This invention relates to relief valves, andwith sage 29 provides communication between the regard to certain morespecific features, to temoutlet chamber 25 and said inlet chamber 23.peranre and pressure relief valves. Another passage 31, in the form of anozzle 33 Among the several objects of the invention may also abnormallyprovides communication between be noted the provision of a simplifiedand compassages 25 and 23 but is normally closed by a 60 pact form ofvalve for pressure-heating systems fusible plug 41. adapted to relieveagainst excessive pressure and From the above it will be seen that threenoroverheating and/or against subnormal pressures. mally blockedcommunications are had between Other objects will be in part obvious andin part the inlet and outlet of the device. 'I'he spring l@ pointed outhereinafterpressed valve blocking passage 29 is adjustable G5 Theinvention accordingly comprises the ele- (see'adjustable shoulder 35 forspring 37) to be ments and combinations of elements, features set atavdesired pressure, say 125 pounds per of construction, and arrangementsof parts which square inch. The valve 19 may be adjusted to will beindicated in the following claim. be opened by the thermostatic disc 'Iat a desired In the accompanying drawing, in which is illustemperature(see adjusting head 39). 'I'he theory 70 trated several of variouspossible embodimentsv of of the adjustment is that as the valve 19 isthe invention, screwed down in its seat, the reaction set up on Fig. 1is a cross section showing one form of the disc 7 causes initialstresses and strains to the invention; be set up in the disc, therebycausing it to react 2o Fig. 2 is a side elevation; to temperature changeotherwise than if not so 75 Fig. 3 is a diagram showing an applicationto Stressed and strained, the variation in temperaa water heatingsystem; and, ture at Which Valve Opening takes place being a Fig. 4 is across section showing a modificafunction of .said stresses and strains.t tion The valve 19 should be set to open at a tern- Similar referencecharacters indicate correperature 10W1` than the fusing temperature of80 sponding parts throughout the several views of the plug 41. thedrawing. A typical connection is shown in Fig. 3 where- Referring nowmore particularly to Fig. 1, vin the inlet 5 is put into directcommunication there is illustrated at numeral 1 a housing to with aheating tank 43, the outlet leading to which is attached a cap 3 servingto form an a suitable discharge point preferably at atmos- 85 inlet 5and to support a cupped, composite, therpheric pressure. mostatic disc7. This disc 7 is formed of discs Operation is as follows: of thegeneral type described in Patent 1,448,240, The Water in tank 43 isheated. Y Under emerdated March 13, 1923, and has a non-developablegency conditions (for example when a gas heater Surface. Its function isto move with a Snap is left on by mistake), the temperature may soaction from the full-line DOSOI! t0 the dQtte rise with or withoutcorresponding increase in line DOStiOn (Fg- 1) at a predetermined Ilse mpressures or the pressure may rise without subempel'atul'e thefeo hstantial temperature rise. At 125 pounds per The disc '7 has the sameaction as said discs of square meh, if the pressure relief valve were 5y plurality of said patented discs in order to obtain increased force ofoperation. In order to fasten the plurality of patented discs, rivetsare sure relief valve may be functioning perfectly at 125 poundspressure; nevertheless under certain used of which the rivet shown atnumeral 11 is emergency conditions of heat input the tempera' ture riseswithout pressure increase. The pres- $0235; zglnng sure relief valvedoes not respond to temperaf being exemplary. At a central opening 13the ture. With the said pressure and metal softendisc '7 preferablyloosely engages with a. groove ing temperature the tank Ordinarilybursts. 15 of a bushing l'l'to-which bushing 1'? is ad- By using thetemperature relief valve 19, set justably fastened a valve 19 seatingatthe inlet to a safe temperature the auxiliary outlet 21 is 105 end ofa passage 21. The passage 21 communiopened, thus permitting escape ofwater. After cates between an inlet chamber 23 which houses theemergency has passed and the temperature kthe disc 'l and an outletchamber 25 which houses recedes with or without the pressure the theraspring pressed pressure relief valve 27, the latter mostat 'l returns toclose the valve 19, thus auto- -e5 seating at the outlet of a passage29. .The pasmatically shutting off an otherwise damaging ne flow, and sodistinguishing from fusible plug temperature reliefs per se.

If the combined areas of the outlets 21 and 29 is not great enough, thepressure and temperature will rise further to the point at which thefusible plug 41 will relieve, thus providing more area without increasein spring size. The fusing point of the plug 41 is higher than that atwhichl plug 41.

I se

Another feature to be noted is that the thermostat '7 opens the valve 19against pressure at the inlet. The snap-acting thermostat, such as heredisclosed provides a more successful and sure opening under theseconditions than will others.

Substitution for the openings 9 may be made by by-passing the disc 7with a suitable passage. Jin` view of the above, it will be seen thatthe several objects of the invention are achieved and other advantageousresults attained.

As many changes could be made in carrying out -the above constructionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description or shown in theaccompanying drawing shall be interpreted as illustrative and not in alimiting sense.

I claim:

A safety relief device comprising a casing having a chamber in opencommunication with a fluid supply and having waste outlet ports fordischarging the fluid from the chamber, a pressure relief valve normallyclosing one of said waste ports against the outflow of fluid butyieldable only under excess pressure to allow the outflow of fluid fromthe chamber, a second valve normally seated under pressure of fluid insaid chamber to close the other port, and temperature-responsive meansfor unseating the latter valve and keeping it open while the temperatureof the fluid in the casing is in excess of a predetermined temperature.

JOHN A. SPENCER.

